1. Field of the Invention
The present invention relates to a discharging valve device for a compressor installed in a refrigeration cycle. More particularly, it relates to an improved discharging valve device for increasing discharging efficiency.
2. Description of the Prior Art
FIG. 1 shows a sectional view of an important part of a conventional discharging valve device for a compressor disclosed in Japanese Examined Patent Publication No. 12909/1972. In FIG. 1, the reference numeral 1 designates a discharging port formed in a housing wall 1a; the numeral 2 refers to a valve seat which is formed integrally with the housing wall 1a at and around the discharge opening of the discharging port 1, the shape of the valve seat being like an upper half portion of a doughnut, in other words, in a semicircular shape having a certain curvature in cross section, the numeral 3 denotes a discharging valve fixture and the numeral 4 designates a discharging valve made of a resilient material, which has one end secured to the housing wall 1a and the other end interposed between the valve seat 2 and the discharging valve fixture 3 thereby to perform opening and closing operations for the discharging port 1 depending on pressure difference produced in a compression chamber (not shown).
In the conventional discharging valve device for a compressor having the construction described above, when gas compressed in a compression chamber (not shown) reaches a predetermined pressure-discharging level, the discharging valve 4 brought in contact with the valve seat 2 formed at the discharging side of the discharging port 1 communicating with the compression chamber is opened due to discharging pressure to thereby discharge the compressed gas through an air gap formed between the discharging valve 4 and the valve seat 2. Then, reduction in pressure in the compression chamber actuates the discharging valve 4 on its closing side to bring the discharging valve 4 onto the valve seat 2 thereby to allow again compression in the compression chamber. Thus, compressing and discharging operations are repeatedly carried out.
In order to carry out these operations smoothly, it is especially essential to prevent phenomena of reversely flowing of gas at the time of closing of the discharging valve 4 on the valve seat 2 and of delay in opening of discharging valve 4 at the time of opening operation. From the viewpoint of assuring the smooth operations, provisions are made in such a manner that an oil film is formed at the contacting area of the discharging valve 4 to the valve seat 2 to increase gas sealing property; the outer surface of the valve seat 2 is so made as to have a certain curvature in cross section, that is, to form an upper portion of a doughnut-like shape so that a circular contacting area is provided between the discharging valve 4 and the valve seat 2; and the diameter of the circular contacting area of the valve seat 2 is made greater than that of the discharging port 1 whereby contacting pressure of the discharging valve 4 to the valve seat 2 is increased.
The conventional discharging valve described above is, however, disadvantageous in that when the gas compressed in the compression chamber is discharged, a lubricating oil is discharged together with the discharged gas, on account of which the oil film spreads in a strip form over the contacting area between the discharging valve 4 and the valve seat 2 to be beyond a predetermined contacting width for sealing, with the consequence of increasing resistance of the oil film due to the spread oil film when the discharging valve is to opened whereby there causes delay in opening operation. This results in increase of input power for the compressor.
Further, there is a problem of noise produced when the discharging valve 4 is actuated for opening operation since resistance of the oil film is large.